It is not simple to make the campaign harder, else we would include it by default in the mod.
My suggestion would be to reduce the recruitment times for the bad factions, and to increase the bonuses to the building named "Ruins" (that is automatically damaged for human factions).
1. Open the file
\alexander\lotrtw\data\export_descr_buildings.txt
Search for "experience_boost"
and increase the values to something like this:
Code:
recruits_exp_bonus bonus 4
construction_cost_bonus_other 50
construction_time_bonus_other 50
law_bonus bonus 4
taxable_income_bonus bonus 50 requires hidden_resource max_city or hidden_resource second_max_city
2. Open this file:
\alexander\lotrtw\data\export_descr_unit.txt
The recruitment times are the first number in the lines starting by "stat_cost"
Use the "search and replace" tool of some text editor to reduce the recruitment times for all factions, except those you are going to play.
Or, a simpler way would be to set all recruitment times to 0, and then use the "house rule" that you as players can not recruit more than 1 unit per turn. I played it this way once.
Search:
stat_cost 8
Replace by:
stat_cost 0
Search:
stat_cost 7
Replace by:
stat_cost 0
... (If I remember 8 is the higher recruitment time in the mod. Repeat until you reach 1)
Search:
stat_cost 1
Replace by:
stat_cost 0